NAME¶

std::destroy - std::destroy

Synopsis¶

Defined in header <memory>
template< class ForwardIt > (since C++17)
void destroy( ForwardIt first, ForwardIt last ); (until C++20)
template< class ForwardIt > (since C++20)
constexpr void destroy( ForwardIt first, ForwardIt last ); (1)
template< class ExecutionPolicy, class ForwardIt >
void destroy( ExecutionPolicy&& policy, ForwardIt first, (2) (since C++17)
ForwardIt last );

1) Destroys the objects in the range [first, last), as if by

for (; first != last; ++first)
std::destroy_at(std::addressof(*first));

2) Same as (1), but executed according to policy. This overload participates in
overload resolution only if

std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true. (until
C++20)
std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>> is true. (since
C++20)

Parameters¶

first, last - the range of elements to destroy
policy - the execution policy to use. See execution policy for
details.

Type requirements¶

-
ForwardIt must meet the requirements of LegacyForwardIterator.
-
No increment, assignment, comparison, or indirection through valid instances of
ForwardIt may throw exceptions.

Return value¶

(none)

Complexity¶

Linear in the distance between first and last.

Exceptions¶

The overload with a template parameter named ExecutionPolicy reports errors as
follows:

* If execution of a function invoked as part of the algorithm throws an exception
and ExecutionPolicy is one of the standard policies, std::terminate is called.
For any other ExecutionPolicy, the behavior is implementation-defined.
* If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation¶

template<class ForwardIt>
constexpr // since C++20
void destroy(ForwardIt first, ForwardIt last)
{
for (; first != last; ++first)
std::destroy_at(std::addressof(*first));
}

Example¶

The following example demonstrates how to use destroy to destroy a contiguous
sequence of elements.

// Run this code

#include <iostream>
#include <memory>
#include <new>

struct Tracer
{
int value;
~Tracer() { std::cout << value << " destructed\n"; }
};

int main()
{
alignas(Tracer) unsigned char buffer[sizeof(Tracer) * 8];

for (int i = 0; i < 8; ++i)
new(buffer + sizeof(Tracer) * i) Tracer{i}; //manually construct objects

auto ptr = std::launder(reinterpret_cast<Tracer*>(buffer));

std::destroy(ptr, ptr + 8);
}

Output:¶

0 destructed
1 destructed
2 destructed
3 destructed
4 destructed
5 destructed
6 destructed
7 destructed

See also¶

destroy_n destroys a number of objects in a range
(C++17) (function template)
destroy_at destroys an object at a given address
(C++17) (function template)
ranges::destroy destroys a range of objects
(C++20) (niebloid)